The invention discloses a novel stacked screw 
sludge dewatering machine and a spiral shaft thereof. The lead angle arrangement order of spiral blades of the novel spiral shaft is that the lead angle gradually becomes smaller from a 
sludge discharge box to a 
sludge feed box, and the lead angle is gradually reduced from 16-22 degrees to 6-14 degrees; the screw 
pitch of a shaft body of the spiral shaft is gradually increased along the direction of the sludge 
discharge box, and from a 1 / 3 position of the 
shaft length of the shaft body of the spiral shaft, the 
diameter of the spiral shaft is gradually increased in a direction from the sludge feed box to the sludge 
discharge box; and an anti-blocking plate, an included angle between which and the centerline of the shaft body is 20-45 degrees, is arranged on each of two sides of the bottom of the spiral blades, and the height of each anti-blocking plate is not less than 2 / 3 of the height of the spiral blades. The novel spiral 
sludge dewatering machine disclosed by the invention can be used for treating 
slurry which is large in proportion, poor in fluidity, high in 
viscosity and easy in agglomeration, expands the treating capacity and application range of a stacked screw 
machine, is more reasonable in screw 
pitch, has a smoother spiral shaft surface, can effectively reduce the 
frictional resistance when sludge passes through the spiral shaft, and can prevent sludge shaft blockage; and a hard 
alloy wear-resistant layer is sprayed on the surface of the spiral shaft, so that the service life of the spiral shaft is prolonged.